by Jim Michaels, USA TODAY

by Jim Michaels, USA TODAY

Few U.S. commanders have spent as much time in Iraq as Gen. Raymond Odierno, the Army's chief of staff.

As a division commander Odierno led soldiers in the days immediately following the 2003 invasion, when the seeds of an insurgency were taking hold. He returned as the operational commander of all coalition forces, leading troops during the 2007 surge strategy that finally blunted a powerful insurgency and nascent civil war. He finished his time as the overall commander for coalition forces, dealing regularly with Iraq's leaders as they struggled to build a government.

Today, Odierno views events in Iraq a bit warily. Violence is growing, driven largely by tension between Iraq's Shiite-dominated government and the country's Sunni minority. A war in neighboring Syria and sectarian tensions elsewhere in the region are only flaming tensions inside Iraq's borders.

"We did what we could," Odierno said during a wide-ranging interview in his Pentagon office. "We gave them the opportunity to succeed."

"The issue we have is there is still a great mistrust between the factions within Iraq," Odierno said. "That's what's causing the violence. I still have hope that this can be worked out."

It was Sunni tribal leaders in western Iraq who joined with American forces and helped turn the tide of war, even before surge forces arrived. Today, those same Sunni leaders are at odds with the government of Prime Minister Nouri al-Maliki.

"I still believe they can be a great country, but they have to solve their differences between the different factions," Odierno said. "They need leadership that allows them to do that."

"That's what I worry about."

Thousands of Americans fought heroically in Iraq, but it's too early to say how the war will be viewed by historians.